Interaction of bone marrow stroma and monocytes

The bone marrow microenvironment is a complex mixture of cells that function in concert to regulate hematopoiesis. Cellular components include fixed nonhematopoietic stromal elements as well as monocytes and resident macrophages, which are derived from the hematopoietic stem cells. Although these monocyte-lineage cells are reported to modify stromal cell function, the reverse also occurs. Given the secretory capability of the monocyte/macrophage and their various potential functions, it is not surprising that stromal cells contained within a particular niche can modify monocyte gene expression and functional maturation. Keywords: cellular response to cell contact and secreted factors Monocytes were isolated from peripheral blood mononuclear cells from 2 different normal donors and cultured for 48h in conditioned medium (CM). The CM was collected from each of two functionally distinct human bone marrow stromal cell lines (HS5 and HS27a) representing different compartments of the bone marrow microenvironment (Roecklein BA, Torok-Storb B. Blood. 1995;85:997-1005). Four samples were analyzed, with two biological replicates for each CM.